Immune surveillance cells in the tumor microenvironment play an important role in inhibiting tumorigenesis and metastasis, but their anti-tumoral effects are impaired. The anti-tumoral effects of innate immune cells and adaptive immune cells in the immune microenvironment of gastric cancer are also impaired. Their degree of functional impairment is closely related to the prognosis of gastric cancer. Multiple factors inhibit the anti-tumoral effects of immune surveillance cells, such as decreased numbers of immune surveillance cells, reduced activating receptors, decreased secretion of pro-inflammatory cytokines, increased apoptosis, elevated expression of coinhibitory molecules on cancer cells or immunosuppressive cells, increased secretion of inhibitory cytokines, impaired antibody-dependent cell-mediated cytotoxicity (ADCC) mediated by antigen-presenting cells (APCs) and pro-tumoral polarization of cells with functional plasticity. These factors can potentially combine to suppress the immune surveillance cells' functions. However, there are conflicting conclusions on the effects of immune surveillance cells on gastric cancer cells. These contradictions are partly due to the heterogeneity of the tumor microenvironment.

肿瘤微环境中的免疫监视细胞在抑制肿瘤发生和转移中起着重要作用，但是其抗肿瘤作用受到损害。天然免疫细胞和适应性免疫细胞在胃癌免疫微环境中的抗肿瘤作用也受到损害。它们的功能障碍程度与胃癌的预后密切相关。多种因素抑制了免疫监视细胞的抗肿瘤作用，例如免疫监视细胞数量减少，激活受体减少，促炎性细胞因子的分泌减少，凋亡增加，癌细胞或免疫抑制细胞上共抑制分子表达的增加，抑制性细胞因子的分泌，抗原呈递细胞（APC）介导的抗体依赖性细胞介导的细胞毒性（ADCC）受损以及具有功能可塑性的细胞的肿瘤前极化作用。这些因素可能会合并抑制免疫监视细胞的功能。然而，关于免疫监视细胞对胃癌细胞的作用有矛盾的结论。这些矛盾部分是由于肿瘤微环境的异质性。